JPS59226213A - Hydraulic lifter of valve gear - Google Patents

Abstract

PURPOSE:To obtain the right actuation of a lifter by exhausting the air separated from lubricating oil in an oil sump chamber by a structure wherein a communicating hole, which is opened on the side surface of the oil pump chamber in order to communicate to an engine lubricating oil passage, is formed by being bored at the position that the upper edge of the communicating hole nearly coincides with the upper wall part of the oil sump chamber. CONSTITUTION:A hydraulic lifter provides with a plunger 3, which is slidably insertedly fitted into a cylinder 2 with its upper end being open, a hydraulic pressure chamber 4 formed by the plunger 3 at the lower part of the cylinder 2, an oil sump chamber 5, which is formed in the interior of the plunger 3 and at the same time communicated through a communicating hole 8 opened on its side surface to an engine lubricating oil passage at all times and a non-return valve 6 arranged between the hydraulic pressure chamber 4 and the oil sump chamber 5. In this case, the communicating hole 8 is formed by being bored at the position that the upper edge 8a of the communicating hole 8 nearly coincides with the upper wall part 5a of the oil sump chamber 5. Due to the structure as mentioned above, the air separated from lubricating oil in the oil sump chamber 5 is quickly exhausted outside through the communicating hole, resulting in ensuring the normal actuation of the hydraulic lifter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a hydraulic lifter provided to automatically adjust valve clearance in a valve operating system for an internal combustion engine.

Depending on the type of valve train, the hydraulic lifter that expands and contracts by hydraulic action is placed between the rocker arm end and the cam in a rocker arm type 0 type valve train, and between the cam and the bushing rod in an OHV type valve train. , swing arm type OHC
This type of valve gear is installed at the pivot part of the swing arm, etc., and basically extends when the cam is not lifted to maintain a constant valve clearance, and when the cam lifts, it is closed by a check valve. By sealing the lubricating oil in the inside 11≦, the extended state is maintained and the lift of the cam is transmitted to the intake and exhaust valves.

FIG. 1 shows, as an example, a conventional hydraulic lifter disposed between the end of a rocker arm and a cam. To be more specific, 1 is a body that is slidably supported by a cylinder head (not shown), has a cam contact portion 1a at the lower end, and has a cylinder 2 with an opening at the upper end, and 3 is the cylinder. This plunger is slidably inserted into the cylinder 2 and has a rocker arm abutting part 3a at its upper end. An oil reservoir chamber 5 is formed therein, and between the hydraulic chamber 4 and the oil reservoir chamber 5,
A check valve 6 consisting of a spherical valve body 6a, a coil spring 6b, and a retainer 6c is provided. Further, a coil spring 7 is disposed within the hydraulic chamber 4, and biases the plunger 3 in the projecting direction with respect to the body l.

On the other hand, the oil reservoir chamber 5 has a communication hole 8 opened in its side surface, and the communication hole 8. Circumferential groove 9 on the outer circumferential surface of the plunger 3. Opening 10 through body 1. Further, it is continuously communicated with a lubricating oil passage of a cylinder head (not shown) through circumferential grooves 11 on the outer circumferential surface of the body 1.

That is, engine lubricating oil is constantly introduced into the oil reservoir chamber 5, and a required amount of lubricating oil is supplied from the oil reservoir chamber 5 into the hydraulic chamber 4 via the check valve 6. When the cam (not shown) is not lifted, the plunger 3 is relatively protruded by the action of the coil spring 7, which reduces the pulp clearance and introduces lubricating oil into the hydraulic chamber 4. Also, when the cam is lifted, the check valve 6 To close the plunger 3, the plunger 3 moves up together with the body 1 and pushes up a rocker arm (not shown).At this time, some lubricating oil leaks from the gap between the body 1 and the plunger 3. Immediately upon completion of the cam lift, the plunger 3 protrudes to replenish the oil pressure chamber 4 with lubricating oil, and by replenishing the oil, the pulp clearance is always automatically adjusted to zero (for example, as disclosed in Japanese Utility Model Application No. 57-2206, etc.).

However, in such a conventional hydraulic lifter, no special consideration is given to the opening position of the communication hole 8 with respect to the oil reservoir chamber 5, and normally the communication hole 8 is opened as shown in FIG.
Since the upper part 8a was located a few degrees lower than the upper wall part 5a of the oil reservoir chamber 5, a large amount of air mixed into the lubricating oil remained in the upper part of the oil reservoir chamber 5. This invention has been made in view of the above-mentioned problems in the prior art, as this accumulated air is not likely to enter the hydraulic chamber 4 during operation and may cause abnormal movement of the lifter. By forming a communication hole that opens on the side of the oil reservoir chamber at a position where its upper edge approximately coincides with the upper wall of the oil reservoir chamber, air stagnation in the oil reservoir chamber is prevented and the hydraulic chamber The purpose is to avoid abnormal movement of the hydraulic lifter due to air intrusion into the hydraulic lifter.

Hereinafter, one embodiment of the present invention will be described based on FIG. 2.

In the embodiment shown in FIG. 2, the present invention is applied to a hydraulic lifter disposed between the end of a rocker arm and a cam, similar to the embodiment shown in FIG. It is substantially the same as the one in the figure, and the same parts are given the same reference numerals.

That is, in this hydraulic lifter, the opening position of the communication hole 8 on the side surface of the oil 1 storage chamber 5 is formed such that the upper portions 1 & 8a of the communication hole 8 are approximately aligned with the upper wall portion 5a of the oil 4 chamber 5. Specifically, in the case of a hydraulic lifter used in a normal automobile engine, the upper edge 8a of the communication hole and the upper wall portion 5a of the oil reservoir chamber
The distance between the oil sump chamber and the upper wall 5a is preferably set to be within a range smaller than 2, more preferably 4, or conversely, so that the upper edge 8a of the communication hole is located slightly above the upper wall 5a of the oil reservoir chamber.

In this way, the communication hole upper id<8a and the oil reservoir upper wall 5
Air mixed into the lubricating oil and separated in the oil sump chamber 5 can be stored in the upper 4 of the oil sump chamber 5 as in the conventional method. First, the oil is pushed out of the right chamber 5 through the communication hole 8, and then quickly discharged to the outside through the fitting gap between the body l and the plunger 3.

Therefore, air does not flow into the hydraulic chamber 4, and normal operation of the hydraulic regulator 7 can be ensured.

The graph shown in Figure 6 is a graph obtained by changing the air mixing ratio of the supplied lubricating oil to find the limit air mixing ratio that causes abnormal movement of the hydraulic lifter.
If the communication holes 8 are formed close to each other by about 2 degrees or less, or conversely, if the communicating holes 8 are formed in an upper position, the critical air entrainment rate is extremely large.

Even if the lubricating oil is mixed with air, which has a relatively large amount of transport,
This ensures normal operation of the hydraulic lifter. On the other hand, when the distance between the two is large as in the conventional case, even a small amount of air mixed in immediately causes abnormal movement.

In addition to the above-mentioned embodiments, this invention also applies to the swing arm 2
It is also possible to configure it as a hydraulic lifter disposed at the pivot part of the swing arm in an HC type valve train or between the cam and bushing rod in an OHV type valve train.It is clear from the above explanation. As described above, in the hydraulic lifter for a valve train according to the present invention, the air separated from the lubricating oil in the oil reservoir chamber can be promptly discharged to the outside, and it is possible to reliably prevent air from flowing into the hydraulic chamber. Therefore, normal operation can be ensured even if the supplied lubricating oil contains a relatively large number of stitches.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a conventional hydraulic lifter, Fig. 2 is a sectional view of a hydraulic lifter according to the present invention, and Fig. 6 is a graph showing the relationship between abnormal interlock occurrence limit air entrainment rate and communication hole opening position. 1... Body, 2... Cylinder, 3... Plunger, 4... Hydraulic chamber, 5... Oil reservoir chamber, 6... Check valve,
7...Coil spring, 8...Communication hole, Fig. 3

Claims (1)

[Claims] if) A plunger slidably inserted into a cylinder with an open top end, a hydraulic chamber defined by the plunger at the bottom of the cylinder, and a communication port formed inside the plunger and opened on the side. In a hydraulic pressure system of a valve train that is configured by arranging an oil reservoir chamber that is constantly communicated with the engine lubricating oil passage and a check valve disposed between the hydraulic pressure chamber and the oil reservoir chamber, the communication A hydraulic lifter for a valve train, characterized in that a hole is formed at a position where an upper edge of the hole substantially coincides with the soil wall of the oil reservoir chamber.